1. Field
The following description relates to a semiconductor device and a fabricating method thereof, and for example, to a semiconductor device with a gate electrode area increased to reduce the resistance at a gate electrode and thus to improve switching speed, and a fabricating method thereof.
2. Description of Related Art
A trench metal-oxide semiconductor field effect transistor (MOSFET) refers to a certain type of transistor in which a channel is formed vertically, and a gate is formed within a trench positioned between a source and a drain. The trench MOSFET includes a lining of a thin insulating layer such as an oxide layer and filled with conductor such as poly-silicon, and provides a specific low on-resistance value by allowing low electric current flow.
An example of the trench MOSFET includes a thick bottom oxide layer formed on a bottom of a trench, and a gate electrode formed thereon. However, since the thick bottom oxide layer is formed by thermal oxidation, Si-induced stress occurs during the fabricating process. Further, due to performing the oxidation under a heat treatment in a temperature exceeding 1000° C., the already-formed well implant profile may alter during the fabricating process, making it difficult to maintain the initially-intended design. As a result, the performance of the device may deteriorate.
To avoid the heat treatment, a high density plasma chemical vapor deposition (HDP CVD) process may be used instead of the thermal oxidation process. When a HDP CVD process is used, a thick bottom oxide layer is formed within the trench by depositing the oxide layer within the trench of the trench MOSFET. However, the HDP CVD process is not a suitable option in certain circumstances. For example, the HDP CVD process requires expensive equipment, causing an increase in the overall manufacturing cost and in the unit price of the products.